Fix for Bug NMS-6447

The notification WebUI is unusable when there are notifications
associated with events that doesn't exist on the DB.

Now, if the event was configured either as donotpersist or with
autoclean="true", a warning message will be added to notifd.log and the
event processing will be stopped.
Merge remote-tracking branch 'origin/1.12'
Fixing log messages after merging 013c4ab65974a0e616990dd43fd3afbf6a65be28